Aushiker wrote:BTW does anyone know how 305 lumens compares to 70 lux reported by Busch & Muller for their light?Andrew

A VERY educated guess (from a neuroscientist cyclist who has a PhD and research fellowship in visual motion perception at Australia's top university) is that increasing lumens over the level of a standard light is unlikely to improve a driver's perception of a bike.

A single point of light, no matter how bright, provides very little information on distance or velocity of the object it is fastened to, and extra lumens can prevent the driver seeing the shape of the object (in this case, a rider and bike).

Aushiker wrote:BTW does anyone know how 305 lumens compares to 70 lux reported by Busch & Muller for their light?

Andrew

From a very uneducated ex carpenter ex greyhound trainer........ the way I understood it, is that Lumen measured the output of the light source, while Lux measured the effective area illuminated by a light source.

When manufacturers provide information of their light in either Lux or Lumen there is no way of comparing the two without knowing the perimeters used to calculate the quoted Lux, such as area illuminated and the angle of the light-beam.

greyhoundtom wrote:From a very uneducated ex carpenter ex greyhound trainer........ the way I understood it, is that Lumen measured the output of the light source, while Lux measured the effective area illuminated by a light source.

The lux (symbol: lx) is the SI derived unit of illuminance or illumination. It is equal to one lumen per square metre.......

....Lumens measure "luminous flux". This is a measure of the total number of packets (or quanta) of light produced by a light source (e.g. a globe or fluorescent tube). This is the “quantity” of light emitted by the light source. The purpose of lux is intended to tell you how many lumens you need given the area you are trying to illuminate.

Lumens is the total amount of light output. Lux measures the intensity of that light in a given area. So 305 lumens may be spread all over the shop, giving a very low lux, or concentrated into a focused beam, giving a much higher lux.

It really depends on what you desire in your headlight beam. I do know that the Supernova E3 Pro with a 305 lumens output is the European 'glare-free lens' and it has a more focused beam, thus giving a higher lux reading I'd expect.

On my road bike I have the first model of the E3 and run a B&M Seculite 1W tail-light (the mudguard-mounted model). With the more recent E3 Pro on the Nomad I have the E3 tail-light, which is very bright as well but doesn't have any reflector. If I had my choice again I'd probably use the B&M Topline Plus.

il padrone wrote:On my road bike I have the first model of the E3 and run a B&M Seculite 1W tail-light (the mudguard-mounted model). With the more recent E3 Pro on the Nomad I have the E3 tail-light, which is very bright as well but doesn't have any reflector. If I had my choice again I'd probably use the B&M Topline Plus.

Okay thanks. I assume that turning on the Supernova turns on the Busch & Muller okay?

warthog1 wrote:This bloke reckons the phillips saferide range of lights are the go. Any experience with them?

Have them (front and rear), love them. viewtopic.php?f=9&t=26723&start=225#p863084The available documentation for them is poor, that's about the only negative. There are undocumented features like battery fault warnings (blinking blue lights while charging) and a low battery warning on the rear light (small green LED that comes on).

warthog1 wrote:This bloke reckons the phillips saferide range of lights are the go. Any experience with them?

Have them (front and rear), love them. viewtopic.php?f=9&t=26723&start=225#p863084The available documentation for them is poor, that's about the only negative. There are undocumented features like battery fault warnings (blinking blue lights while charging) and a low battery warning on the rear light (small green LED that comes on).

Motorcyclists, even when running headlights at all hours, still don't run high beams that dazzle oncoming drivers. Bicycles shouldn't either. Not to say that you shouldn't have lots of lumens, but they should be spread flat and wide where you need them. The ~7000 lumens from my BMW are far less irritating than the ~500 from a Magicshine.

MattyK wrote:Motorcyclists, even when running headlights at all hours, still don't run high beams that dazzle oncoming drivers. Bicycles shouldn't either. Not to say that you shouldn't have lots of lumens, but they should be spread flat and wide where you need them. The ~7000 lumens from my BMW are far less irritating than the ~500 from a Magicshine.

Less irritating to you. I find some car headlights to be way too intrusive, and brighter than most bicycle lights.

VRE wrote:Less irritating to you. I find some car headlights to be way too intrusive, and brighter than most bicycle lights.

Which cars? Specific models, or just random individual cars? If the latter, it's likely not a design issue, more likely a particular user issue (eg incorrect aiming, or fitting HID globes to a system designed for incandescent filaments)

On bicycles the current crop of concentric beam 'marsupial-fryers' are a regular concern for many bike-path commuters. I have seen some that are definitely brighter than car headlights ie. I've seen them on the road, alongside car headlights, which, despite greater wattage, have design-standard optics to prevent dazzle.

At the same time I have been driving when a following car has had headlights (in urban streets on low beam) that are so penetratingly bright to be a real distraction and irritation. So much that I have been forced to dip the rear view mirror. These are generally recent model cars, often European, with those ultra-white HID lights. There is something about their beam features that is 'over the top'.

Chris249 wrote:... extra lumens can prevent the driver seeing the shape of the object (in this case, a rider and bike)

Which can actually be a GOOD thing: if the motorist believes a motorbike, not a bicycle, is approaching, they tend to treat it with more respect. Sad, but true.

+1

That has been my experience, as I have posted about elsewhere.

The problem is that if the driver sees only a single point then they have no way of knowing how far away the object is, or the speed at which it is moving. See, for example, "Automotive Lighting and Human Vision" by Wordenwerber et al.

Therefore if your light is bright enough to effectively destroy the driver's ability to see the rider, you are taking away vital information about your position and speed.

Secondly, motorists have MASSIVE problems interpreting the speed of motorcycles by their headlights, and can easily be out by some 60% or more - see "Judgments of approach speed for motorcycles across different lighting levels and the effect of an improved tri-headlight configuration" by M. Gould a, D.R. Poulter b, S. Helman c, J.P. Wann. So it appears that there's little solace to be found in dazzling drivers into thinking you are a motorbike.

I'm no expert in these things, but I'm married to someone who has a PhD in the accuracy of visual perception of moving points of light, was top honours student out of about 5,000 undergrads at her uni, has a fellowship at Australia's top university, rides each day, and lost her previous husband when his bike was struck by a car in low-light conditions. Although she has not looked at this issue specifically, her gut feeling is that extra power does NOT equal safety. I think I'll take such an expert's point of view on this.

There's very little that is straightforward and predictable about human vision and visual perception and processing. Given the market in powerful bike lights, one would have thought that the manufacturers could have provided some evidence that their products actually increase safety. At the moment there appears to be no evidence that they do.

The 'marsupial-fryers' started out as lights for off-road night MTB rides, where illuminating every square inch of the rough track ahead of you is essential. There are very few other vehicles to warn/dazzle so the bright output and concentric beam is not an issue - the higher beam is even beneficial to illuminate overhead branches that may wipe you off the bike.

These same lights have been transferred to road bikes with no modification of the beam to produce a road beam. Road beams require a good optic design (mostly in the reflector) to throw a bright beam onto the road to light up the surface and any hazards, but give a dimmer throw of light ahead into drivers/riders eyes to identify your presence on the road. There is a clear horizon to the beam that you can see in beam shots.

The new (about to be released) B&M Luxos

Speed judgement by others is always tricky with just one light - an argument for having two headlights of lower intensity and good reflective materials.

The ancient Cate-eye HL500 of 1990 - while a dim performing battery light compared to the current crop, it probably had much better optics for road use. Optic design is something today's battery headlight designers seem to have flunked at uni.

Any E3 users (dynamo powered) had issues with their lights yet?My E3 Pro front is fine but the E3 tailight failed altogether (thank heavens I always run backup lights) and I noticed that the standby light for both was also not illuminating once I got home and parked it up in the garage - i'm thinking the capacitor has gone? Has done 11,000+km.

I've used mine for about 3000km with no problems so far. I wouldn't bother with a rear light again - the E3 tailight has little side visibility and I prefer a brighter flashing light anyway. And no wiring clutter on the bike frame.

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